Bhagavad Gita
6.43

तत्र तं बुद्धिसंयोगं लभते पौर्वदेहिकम् । यतते च ततो भूयः संसिद्धौ कुरुनन्दन ॥

tatra taṃ buddhisaṃyogaṃ labhate paurvadehikam | yatate ca tato bhūyaḥ saṃsiddhau kurunandana ||

Translation

There, one regains the connection of the intellect from the previous life, and one strives again from there toward perfection, O joy of the Kurus.

Interpretation

The continuity of spiritual progress is preserved across lives. In the new birth, the previous life's buddhi-samyoga (connection of the intellect with yoga, the spiritual orientation developed through practice) is regained. This manifests as spiritual inclination, ease with meditation, natural dispassion, and attraction to wisdom teachings in the new birth. The yogi picks up where they left off and strives with fresh energy toward samadhi (samsiddhim — perfection). No genuine spiritual progress is ever lost.